The present invention relates generally to atmospheric/cloud physics, and, in particular, relates to hydrometeors therein.
It is a well known fact that the atmosphere of Earth and other planets is not purely composed of just gas, of whatever density, but has therein particulate matter such as raindrops, snow, graupel, hail mist, cloud vapor, cloud ice, dust from dust storms and volcanoes, meteoric dust, atomic debris, etc.
One type of prior apparatus used for this endeavor is an air towed pre-weighed filter placed within a housing having an air scoop. This apparatus is towed through the air for a given distance to collect a given volume of air. After, the filter is again weighed to determine the difference in weight which can thus be attributed to the dust collected. Clearly one could select filters having different mesh sizes or one could examine the collected dust to determine particle size ranges in one filter.
A further limitation is that the weighing must take place after the flight. This apparatus is thus limited to particulate matter which does not evaporate. Another limitation is that the actual filter must be weighed afterwards. The spacial-temporal resolution of such device is extremely large and unsatisfactory. An example of this prior apparatus is disclosed in U.S. Pat. No. 2,468,021 which is incorporated by reference.
Other apparatus used to collect particulate are mounted on or near the ground and are fed by gravity or forced air flow. Such apparatus are disclosed in U.S. Pat. Nos. 3,216,246 and 3,104,542 which are incorporated by reference.
This type of apparatus has several disadvantages. For one, they are stationary and near the ground thus limiting the types of samples collected. For example, radioactive material may stay airborne for long periods of time and thus cover long distances and eventually coming to the ground where there are no collectors. Further, meteorological conditions near the ground collector such as winds may distort the sample.
The above disadvantages have motivated a search for an apparatus that minimizes the above disadvantages as well as having additional features that provide advantages over the prior art.